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Sulfide concentration and the growth of sqr expressing strain Synechococcus sp. PCC 7942

The horizontal axis stands for day passed, while the vertical axis is the absorbance of an OD 730nm. According to the graph, sqr expressing strain grew much better than wild type strain when sulfide was added into the medium. This result suggests that sqr is not only expressed but functional in the cyanobacteria.

Standard curve

We established a H2S standard curve to quantify H2S concentration inside our experiments.

Lab Incubation with Escherichia coli

(1) Different Concentration under 24HR

We used different H2S concentration challenge ptrc-sqr transformed E.coli and tested H2S consumption in 24hrs. The result shows that ptrc-sqr transformed E.coli consumed much more H2S compred to the blank control, ptrc-str transformed E.coli. In other words, we believe our sqr gene works!!


(2) Different Concentration under 48HR

We followed the experiments in 48hrs and analyzed the H2S consumption in different groups. As the same as our expected, in 48hrs, our ptrc-sqr transformed E.coli depleted much more H2S than 24hrs timepoint.

Differences Between 24 HR and 48 HR under Same Concentration of H2S

(1) 500mM H2S

If we analyze two group in the same H2S concentration, it’s easier to find out that our ptrc-sqr transformed E.coli consumed H2S dramatically.


(2) 250mM H2S

The experiment result are the same as previous group, ptrc-sqr transformed E.coli can consume much more H2S.


(2) 125mM H2S

This diagram illustrates that even at a concentration of 125mM of sodium sulfide, the difference of consumption rate is obvious between sqr expressing strain and wild type one.

References

Facultative Anoxygenic Photosynthesis in the Cyanobacterium Oscillatoria limnetica YEHUDA COHEN,* ETANA PADAN, AND MOSHE SHILO Department of Microbiological Chemistry, The Hebrew University-Hadassah Medical School, Jerusalem, Israel Received for publication 9 May 1975

Sulfide oxidation in gram-negative bacteria by expression of the sulfide–quinone reductase gene of Rhodobacter capsulatus and by electron transport to ubiquinone Hiroomi Shibata and Shigeki Kobayashi 2001

Sulfur metabolism in Thiorhodoceae. I. Quantitative measurements on growing cells of Chromatium okenii. Antonie Leeuwenhoek, 30: 225–238 Trüper, H.G., and Schlegel, H.G. 1964.